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A ril 20, 1926. j 1,581,509 K. BUNGERZ TELEPHONE RECEIVER Filed Dec. 21920 //7V@ /7 70 r: Adr/ 5407 e #2 2 is a Patented Apr. 20, 1926. I

UNITED STATES v 1,581,509 PATENT OFFICE.

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Application Med December 2, 1w. Serial no. 427,:05.

To all whom it may concern:

Be' it known that I, KARL BUNGEBZ, 'a citizen of the United States,residin atthe townvof Hempstead, in the county of assau, State of NewYork, have invented certain new'and useful Improvements in TelephoneReceivers, of which the following is a full,

clear, concise, and exact description.

This invention-relates in general to telephone receivers andparticularly to that type of receiver' which employs no permanentmagnet.

General use has in the past been confined to-telephone receiversemploying permanent magnets in conjunction with electromagnetic coilsfor influencing the receiver diaphragm.

Another type of receiver which is becoming more widely used is that inwhich no permanent magnet is employed, a constant magnetism beingfurnished by an electromagnet. Such receivers are usually connected inseries with the line, and the current for supplying the magnetism isfurnished, from the central oflice. V The present invention relates toelectromagnet receivers of this type, adapted for use on high efliciencysubstation circuits.

The object of the invention is to provide a receiver of improvedefficiency, and one which may be manufactured economically. In. thepreferred form of the invention,

a magnet structure is provided which comprises an outer iron shell madeof a punchmg, and an inner pole which is made of two punched iece's ofsilicon steel. These two pieces an the outer iron shell are weldedtogether. The unita core structure thus obtained is a considera eimprovement from a magnetic standpoint, and is alsomechanically-superior now in use.

In the drawing, Fig. 1 is a longitudinal section of the tele honereceiver setting forth the features of rspective view of the assembledmagnet p es; and Fi 3 is a perspective view showing separate y the twopoles of the magnet As is shown in Fig. 1 of the. drawing, the receiveris internally a self-contained unit, consisting of the brass cup 4 formounting the magnetic system and for providin a dia hragm clamping seat.The cup 4 as a ange 5 which forms a seat for the diaphragm 6. Thediaphragm is clamped in place by a brass screw cap 7 which engages thethreads on the cup 4. The cap 7, which the present invention;

is made. in the form of a grid to protect the diaphragm, engages'thecircular edge of the receiver passing 8 thereby serving to locate theinner unit within the shell.

The electromagnet of the receiver comprises a coil of wire 9 which isslipped over a core 10 of silicon steel formed of a plurality ofseparate segments magnetically connected in such a manner as to reduceeddy-current loses. These segments constitute one pole of thema net. Thecoil 9 is surrounded by an outer s ell 11 consisting of .a splitcylindrical shell preferably of soft iron, to the flan e 12 of which arewelded the bases 13 an 14 of the inner pole segments forming pole 10, asshown clearly in Fi 2. This outer shell 11 constitutes the ot er pole ofthe magnet. Silicon steel has been found to possess the necessarymagnetic characteristics to render it suitable for the core material,but other materials having such characteristics as to produce thedesired result may be used. It is extremely pole and are substantiallyat right angles thereto. In the accompanying drawing the flan'e 12 ofthe outer shell 11 is shown wel ed to the base sectors 13 and 14 of theinner pole 10., Practically the same results ma be obtained by fasteningthe parts toget or by means of screws threading into the brassresonating cup 4. It may be said, however, that the welds serve thedouble function of providing for the continuity of the magnetic circuitand of making a single unitof the three parts.

When the magnet unit is mounted in the bell of the receiver, the fourscrews 15, only one of which is shown, are used for mounting and alsoserve to insure the continuity of themagnetic circuit "by clampingtogether the component parts of the welded assembly. The coil 9 is heldin place with corresponding ring segment of the inner shellac or anyother suitable material. The

rubber plug 16 which is forced between the ring segments of the innerpole, and is fastened with shellac, serves to maintain the and the core.

gap between the se ments. The coil 9 is placed in position with theleads 17 issuing from the underside thereof rather'than from the top,the object being to keep the wires from coming in contact with thediaphragm and from getting in between the diaphragm To compensate forthe weight of the permanent magnets which are omitted in the receiver, acast lead weight 18. is attached by 'means of detachable bolts 19 .to

the back of the cup 4. Binding posts 20 for attaching tubular or spadetips are mounted on a block of insulating, material 21 which is held tothe receiver cup by-the bolts 19 which hold the weight 18 in place.

The unitary core structure herein disclosed is economical and easilyconstructed.

Because of the compactness of the magnet.

system, it has been possible to design a receiver which, being aself-contained unit, will fit directly into the shell of most receiversin common use, and is held therein by the usual receiver cap 22. Thusthe inner unitQwill function as a telephone receiver even if the outershell and cap are destroyed.

' netic iron and an inner pole of much smaller cross sectional areaformed of a plurality of Ion itudinal silicon steel segmentssubstantialIy in cylindrical formation centrally disposed Within saidouter pole.

4. In an electromagnet core structure, a,

pole comprising a plurality of magnetically separate longitudinalcylindrical segments su stantially in cylindrical formation and a baseconsisting of a' plurality of sectors of magnetic material outwardlyextending and integrally formed with said corres onding segments andsubstantially at rlght-angles thereto.

usual.

of longitudinal segments, a coil or,

* ralit 5. In an electroma et core structure, a pole comprising a splitcylindrical shell of magnetic material having an outwardly extendingflange substantially at right-angles thereto and an inner pole having aflange engaging the flange on said outer pole piece an secured thereto.

6. In an electromagnet, an outer pole in .the form of a splitcylindricah ring, an inments, an a coil or winding mounted there- 1 onfor operating said diaphragm, said coil and secondnamed pole beingdisposed within said cylindrical shell.

8. In an electromagnet core structure in combination, a pole comprisinga plurality of longitudinal segments of magnetic material substantiallyin cylindrical formation and a base cons sting of a plurality of sec--tors of magnetic material integrally formed with said segments andsubstantially at right-angles thereto; and a pole comprising a splitcylindrical shell of magnetic material and a flange integrally formedtherewith and substantially at right-angles thereto.

9. In an electromagnet core structure, a substantially circular outerpole comprising a split cylindrical shell of magnetic material and abase comprising an outwardly extending flange substantially at ri htangles thereto, an inner pole ormed o a plurality of magneticallyseparate segments bf silicon steel substantially in cylindrical form andhaving a base consisting of a pluof sectors of magnetic material integray formed with said oorrespondlng segments and substantially at rightangles thereto, said'two poles being so disposed one to the other thatthe flange of one is in superposition with respect to the base of theother.

In witness whereof, I hereunto subscribe my name this 23rd day ofNovember, A. D.

'. KARL BUN GERZ.

